This invention relates to a viewfinder for confirming an image pickup range of an image pickup apparatus and, more particularly, to a viewfinder of a small size and a small thickness suitable for use with a digital image pickup apparatus, such as a digital still camera or a digital video camera, and an image pickup apparatus which uses the viewfinder.
Image pickup apparatuses such as a digital still camera and a digital video camera include an image pickup block and an observation block. The image pickup block records an optical image formed by an image pickup optical system. The observation block confirms the image pickup range of the image pickup section. Recently, the observation block is configured popularly such that an image pickup range is displayed on a LCD (Liquid Crystal Display) panel to be observed directly by an observer for the confirmation of the image pickup range.
On the other hand, several users still have a strong demand to use a viewfinder as an observation block, and many digital still cameras satisfy the demand by incorporating an optical viewfinder.
Meanwhile, digital video cameras and some digital still cameras incorporate an electronic viewfinder which expands an image displayed on a small-size LCD device using an eyepiece system to allow confirmation of an image pickup range.
In recent years, as the compaction of digital image pickup apparatuses proceeds, a reduction in size is demanded also for the observation block. Particularly for digital still cameras, a strong demand is directed to a reduction in thickness; and a demand for miniaturization and a reduction in thickness is directed also to a viewfinder.
Meanwhile, also, a higher power variation exceeding three times is demanded for a digital still camera in recent years; and, also for a viewfinder, miniaturization and a reduction in thickness while achieving a higher power magnification are demanded.
However, if a conventional optical viewfinder is used as the observation block for the image pickup apparatus described above, then in order to assure a high variable power, an increase in the size of the optical system cannot be avoided. Consequently, the demand for miniaturization cannot be satisfied.
Further, where an optical viewfinder of high variable power is used, when it is used with a high magnification, the variation of the diopter scale by the distance to the subject is so great that the user cannot observe an image well through the viewfinder. Even if a diopter scale adjusting mechanism is provided for the optical viewfinder, since the diopter scale adjusting mechanism must be used to adjust the diopter scale in accordance with the distance to the subject every time, the convenience in use of the viewfinder is very low.
One of possible solutions to the problems described above is to incorporate an electronic viewfinder. If an electronic viewfinder is used, then not only miniaturization and higher variable power can be achieved, but also an improvement in performance can be anticipated in that the diopter scale does not suffer from variation and no parallax appears. Further, thanks to the development of a LCD panel having a high luminance, the visual observability of an image is being improved significantly.
A representative one of the small-size electronic viewfinders is disclosed in Japanese Patent Laid-open No. 2002-303803 (hereinafter referred to as Patent Document 1).
In the electronic viewfinder of Patent Document 1, the power arrangement of lenses which form an eyepiece system is optimized in order to miniaturize the electronic viewfinder. However, where the configuration of the electronic viewfinder is used, it is very difficult to achieve a reduction in thickness.